<!DOCTYPE HTML>
<html>
<head>
  <script>
    function tweak() {
      var shadowDiv = document.createElement("div");
      shadowDiv.style.border = "10px solid green";

      var shadowRoot = document.getElementById('outer').attachShadow({mode: 'open'});
      shadowRoot.appendChild(shadowDiv);

      var orangeDiv = document.createElement("div");
      orangeDiv.style.border = "10px solid orange";

      var purpleDiv = document.createElement("div");
      purpleDiv.style.border = "10px solid purple";

      shadowDiv.appendChild(purpleDiv);
      shadowDiv.insertBefore(orangeDiv, purpleDiv);
    }
  </script>
</head>
<body onload="tweak()">
<div id="outer">
  <div style="background-color:red;"></div>
</div>
</body>
</html>
